The Mistake
by Harvey Elwood
Summary: Warning: graphic descriptions of M/M sex. A Sherlock/Lestrade fic. Sherlock uses sex as a coping skill to stop him from relapsing when he's triggering. Lestrade uses sex to get back at his cheating wife.


**Author's Note - **This story contains M/M smut. Sherlock/Lestrade.

**Disclaimer - **I don't own anything Sherlock-related. The only thing I own is the bit at the very beginning when Sherlock is thinking of his time in rehab, those characters are mine. Also, I live in America, so my English English slang is probably off.

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There were two reasons why it started happening between them, the first one was because of something that one of the therapists had told Sherlock when he was in rehab for his drug use. "You need to have coping skills for when you get triggered," she had said to the room, it was a group therapy session, "it's hard to stay clean, and getting triggered and wanting to use again is only natural. When this happens you need to do something to get your mind off it."

The therapist went around the room and made everyone tell the group one of their coping skills. "Playing guitar, or any instrument," said the meth addict in the corner.

"Writing in my journal," said the girl that had _many _different poisons.

"Um, doing…yoga?" said an androgynous looking fellow that had a taste for weed, glue, coke, rum, and heroin.

_"Sex," _hissed the girl in the back that not only had tracks on her arms but lines from where she'd taken a razor to her skin.

The crowd had laughed, you would have thought that maybe the therapist would have said that was a negative coping skill because it could lead to things like STDs and babies. The therapist just smiled and nodded, "Yes, sex is a coping skill."

Sherlock had looked over that and the entire meeting and his whole stay in rehab. He understood the message: _drugs are bad._ He didn't stop because Mycroft wanted him to stop, though. He didn't stop because it was illegal to snort coke. Bollocks to that, he stopped because of a very bad trip into his Mind Palace one day that _anyone _could figure out was because of the drugs. So he stopped. He stopped to protect his mind.

He wasn't going to bullshit himself though. Quitting is hard. So, he needed a coping skill to never get back on again. He needed sex.

That was something that he never told Mycroft or John or Molly and _definetly _not Mrs. Hudson about. He turned into a slag. Going out and picking up women or men when he could find the ones that seemed interested. Sherlock knew he was attractive, and was thankful for that fact when he was triggering and horny.

_"Come back to my flat," _he'd say, with his hand against the wall, leaning up against his new bed-mate, _"I might have a few things to show you."_

The second reason that it started happening was because of Lestrade's ending, failing marriage. If you've ever seen _The Rocky Horror Picture Show _(and you should have by now if you're reading smut) you'll know that the Inspector (the man sitting at the desk between shots of Brad and Janet on their adventure) says that emotions can make you a slave to them. That was why when Janet saw the tape of Brad, her fiancé cheating on her with Dr. Frank N. Furter (even when she'd just cheated on Brad with Frank N. Furter) she looked for revenge. Revenge was in the form of having sex with a six hour old "cut and hunky" machine named Rocky in an incubator.

Lestrade's wife was cheating on him, there was no way Lestrade could deny this anymore, even if he wanted to. He was frustrated, angry, sad, depressed, and betrayed. Then opportunity came knocking on his office door.

Sherlock didn't actually knock though, he just flung open the door to Lestrade's office. It was eleven o'clock at night, and the Detective Inspector was working late _yet again. _

_ Maybe that's why she left me, _he thought sadly to himself.

"I can't help that I work late," Lestrade had said to his wife, "I wish I didn't, it's tiring work, but I have to."

"London doesn't need you, Greg," she had hissed, "_I do."_

"Bollocks, bollocks, bollocks," Greg had growled into his paperwork, with his head on his desk, he began to cry frustrated tears.

He hadn't heard Sherlock come in, and Sherlock stood in the doorway, _actually surprised_. Sherlock had been triggering, he wanted some coke to snort, he'd never needed it more. But, he wasn't having any luck at clubs (for the first time in his life). All the men he had pursued had pushed him away with choruses of "sorry, I'm not gay," and "I don't swing that way," there was more than one, "I don't play for your team," and one infuriating, "I already have a boyfriend."

He thought that if he couldn't find someone to bring home he would go and see if he could look through the files of cases in Lestrade's office.

That was when he figured…it was an opportunity to make not only himself feel better but also Lestrade. Of course, he'd heard around, having sexual relations with a co-worker was the worst thing someone could do on the job, but right now, Sherlock wanted nothing more than to make that mistake.

He turned on the charm, pretended for once to be a normal human, not a sociopath. He came over to Lestrade with silent steps and put one hand on Lestrade's shoulder. Greg jumped and looked up immediately to see Sherlock standing over him.

As he furiously wiped his tears from his face, he whined, "Sherlock, you scared me half to death. What are you doing here?"

Sherlock brought a chair over to sit down with the DI without breaking eye contact, "I could tell that you weren't doing well," Sherlock bullshitted, "I could feel it."

"You? Sympathy? Please," Lestrade said, still embarrassed to be caught crying.

"I'm not completely without feelings," Sherlock shook his head, his eyebrows knitting together in fake empathy, he was rubbing Greg's back as he said this. Greg and Sherlock's faces close together, Sherlock put a hand on Greg's knee.

"Sherlock, I –" Lestrade shook his head angrily, "you're not supposed to _be _here."

"I needed to be with my friend," Sherlock whispered. With this Sherlock was rubbing his hand up and down the inside of Greg's thigh.

"Sherlock, what are you doing?" Greg asked, looking curiously at Sherlock's hand as it got closer with each stroke to his crotch.

"I'm just letting you know that I'm here for you," Sherlock whispered into Greg's ear, "in any way you want me to be."

"Sherlock my – " Lestrade had said it in an attempt to tell him to get off, but then he thought about it and the last word came out in icy anger, _"marriage."_

"Is that what's bothering you?" Sherlock asked gently, "It's your wife, isn't it? What's happening?"

Instead of slumping away, Greg allowed Sherlock's hands to continue rubbing his skin, as he said, in anger, _"My wife has been cheating on me."_

"Cheating on you?" Sherlock feigned surprise.

"Yes, with some bloke that she sees on the weekends, I don't know his name or anything about them, I just know they've been shacking up _every single weekend," _Greg clenched his teeth shut and that's when the anger flowed out of him, with each word in "every single weekend" he pounded his fist into his desk.

If this was any other situation, Sherlock would be in a flurry of questions _How do you know? When did you find out? _But right now, Sherlock was trying to get in his pants.

Sherlock couldn't get a word in after that, because Greg leapt up and started pacing around the office, screaming, _"Haven't I been a good husband?! _I mean, I've been with her through everything, I've known her pretty much my entire bloody life. I work late! I work late because I want to be able to support her! I want to support our kids! Our family! Keep a roof over our heads! I'm doing it because I love them, not because I hate them and want to be away from them all the time! You know, quite the opposite, I want to be with them _all _the time! I love my family! I love her but she – but she – but she-"

"But she what, Lestrade?" Sherlock egged him on, trying to bring the anger out of him.

_"She started fucking someone else!" _Greg screamed, "I wanted her to be fucking me! I wanted to fuck her! But instead she just, what, throws me away? Am I a toy she's done with? Is she bored with me? What? What am I supposed to do, Sherlock?"

Sherlock was standing up in an instant, closing the distance between them, bodies just feet apart. "You get back at her, Lestrade," Sherlock said, "Make her feel what you're feeling right now! Don't you want her to see how you feel?"

"Of course I do, but – "

"But nothing!" Sherlock said. _God, I love being a bad influence. _"You want her to understand where you're coming from, then you need to put her _where _you're coming from."

"Yes," was all Greg said, nodding.

"Then what are you waiting for?" Sherlock asked. It was exactly the invitation Greg needed in that second.

Greg pushed Sherlock onto his desk, some of the stacks of files thumped to the floor, Greg's hands were in Sherlock's curls in an instant and they were snogging furiously. Sherlock and Lestrade were growling against each other's lips, Sherlock in sexual desperation, and Lestrade in anger.

_God, this took way too long, _Sherlock hissed in his mind.

Sherlock's hands were all over Greg, on his back, in his hair, on his bum. Sherlock pressed his cock hard against his lover's crotch, feeling the hard-on that was gathering in Greg's pants. "That's it," Sherlock growled into Lestrade's neck, wrapping his legs around the Detective's waist.

Breathing hard, and labored, Greg's hands flew down to the front of Sherlock's trousers. He began un-buttoning and un-zipping, and Sherlock groaned, "Yes, yes, yes," as he did it. Greg furiously pulled off Sherlock's pants and trousers, his cock springing out in front of them.

"Someone's hard," Lestrade said, biting onto Sherlock's shoulders and collarbones. Sherlock hummed appreciatively, put his hand down the Detective Inspector's pants (which got a gasp out of him) and said, "Yes, you are."

As Sherlock started tugging at the Detective's cock, Lestrade groaned, his hips moving on their own. "Let me fuck you, Sherlock, _let me fuck you."_

"Do it," Sherlock growled through clenched teeth, _"and you'd better do me hard."_

Greg pushed his trousers and pants down his thighs just enough to get his cock out, he shoved two of his own fingers into Sherlock's mouth and Sherlock sucked and licked them needingly, knowing what was coming. With his other hand, Greg spit onto it and rubbed the saliva onto his cock.

"You want me to suck you?" Sherlock asked.

"No time for that," Greg shook his head and pushed the two lubricated fingers into Sherlock's hole at the same time.

Sherlock screamed out in pain. _He doesn't know how to have gay sex, fuck, at least he fucking let me suck his fingers. _

Before he knew it, Lestrade had pushed his cock into Sherlock without even bothering to try to find his prostate. Sherlock let out another scream as his muscle was breached rather harshly.

"Like that, don't you?" Greg said with a guttural moan, licking Sherlock's neck.

Sherlock, instead of answering, wriggled around on the desk, trying to get Lestrade's cock to push up into his sweet spot.

As soon as Lestrade's cock was pushing up right where it needed to be, Sherlock demanded, "Harder! Come on, right there!" As time went on, Greg was leaving almost permanent bite marks and hickey's on Sherlock's neck. Sherlock screamed louder, demanding more.

"Come _on, _Lestrade! Wreck me! Wreck my arse! Do me hard!"

"You wanna be done hard?" Lestrade growled.

"Yes!"

Greg unexpectedly pulled out of Sherlock, and flipped him over on the desk, so he was face-down on top of it. Greg's hand was on the back of his head, pushing him down hard. Sherlock screamed again as Greg pushed back into him, Sherlock dug his nails into the desk and groaned as Greg fucked into his prostate each time he thrusted.

Sherlock came in thick ropes onto the detective's desk.

"Fuck," Lestrade moaned and shot out a load of cum into Sherlock's arse. Then he fell on top of the heavy-breathing Sherlock.

They rolled off each other and, knees buckling, were sitting on the floor, catching their breaths. Sherlock thrusted up his hips and pulled up his trousers and pants. He crawled onto Lestrade and kissed him, biting his lips and licking them.

"Was that your first time with a man, Detective?" Sherlock asked, standing up.

"Yes," Lestrade looked guilty and embarrassed.

"Well, you were good," Sherlock complimented, although in his head, he was thinking, _Except use one finger at a time and go in slower, arsehole. _

"Oh no," Lestrade groaned.

"What?" Sherlock asked, uninterested. He'd gotten his fuck, he'd be okay until the next time he triggered.

"That was a mistake," Lestrade said with dizzying realization.

"It's okay, I don't have any STDs and I hardly think I'll get pregnant," Sherlock scoffed.

"It's not that," Lestrade said, finally picking up his own garments and standing, if not weakly.

"What, _you're _pregnant?"

"Shut up, Holmes," Greg snapped, "This didn't help at all. This isn't good. I want my marriage back!"

_Well, of course it wouldn't help, _Sherlock thought.

"Sherlock, look," Greg said, bending over to pick up all the files that had fallen to the floor from the hardcore fuck, "this didn't happen, okay?"

"Of course it happened, Lestrade," Sherlock rolled his eyes, "but I'm _assuming _you mean you don't want me to talk about it."

"What happened to you?" Lestrade asked suddenly, "I thought you were 'here for me'."

Sherlock stayed quiet, then went to the door. "Text me if you have a case," he said.

"Sherlock!" he yelled, "You knew I was going to be here, didn't you? What? Was this all you wanted? Am I just a one night stand to you?"

"Hardly," Sherlock growled, "You're also my Detective Inspector. I will see you the next time we have a case, and don't worry, this 'never happened'."

After Sherlock closed the door behind him and started his long walk home to his empty flat that he had alone and shared with no one, Lestrade was still in his office, consoling himself, "It never happened," he said, "it never happened and it can't happen again."

It did happen again.

It happened a lot.

The next time, Lestrade had just moved into his new flat, a one-room, all by himself. He needed company, and he begged Sherlock to come over because he couldn't think of anyone else.

It ended in Lestrade making himself a crying mess on the couch and Sherlock holding him and rolling his eyes.

"Detective," Sherlock growled, "if I give you a blow job will you shut up?"

"What?" Lestrade asked, "Sherlock I don't want you to give me a blow job if you don't want to I mean you've already come over here and that's nice of you enough and ah-ah-_ahhhhhhh."_

Sherlock had gone down on Lestrade and started sucking on the tip of his cock. He'd licked up the under-side of it and started to swallow down it. Sherlock wasn't yet perfect at giving oral (to males) but he did try to push himself down as far as he could possibly go without gagging. This time, Sherlock could only make it three-fourths of the way down his cock without gagging.

"Are you okay?" Lestrade had asked with heavily-lidded eyes down between his thighs after he heard Sherlock's throat kick. There was a string of saliva connecting Sherlock's lips and Lestrade's angry red cock.

"I'm fine, just shut up and enjoy it," Sherlock said and swallowed it down again.

After a long bout of Sherlock sucking in his cock, licking and inhaling his balls, and breathing in the skin around his sex, Greg came powerfully onto his own stomach and Sherlock lapped up every bit of cum – keeping his eyes on Lestrade's.

"Why do you have to be so sexy?" Lestrade groaned.

"We can keep doing this," Sherlock said, getting off his knees on the floor, he told Lestrade to pick up his hips so he could push his trousers back up.

"No, we ca-" Lestrade tried to say.

"Face it, Detective," Sherlock said harshly, "You're marriage has ended. You're in a one room flat by yourself. Your marriage is gone, over. We can keep doing this though. Anytime you have a case or want a fuck, just text me. I'll text you for the same, okay?"

And with that, Sherlock left.

Lestrade found himself, alone, in a flat, an ended marriage, a tiring job, and now with the status as Sherlock's call boy.

"Not true though," Greg held himself, "Techinically he's my call boy too."

The next few times included naughty texting between each other and rolling around on either Sherlock or Greg's bed.

The final time was when Sherlock was working late in the office with Lestrade. Everyone had just left so it wasn't that late, it was sometimes around nine.

"It's okay, we'll lock up," Lestrade had told a co-worker.

"All right, Detective," the co-worker nodded, "you two have a good night."

"Lestrade," Sherlock said, a half an hour in, "we're along."

"Yes," Detective said without looking up from the papers.

Sherlock plunged his hand down Greg's pants and started furiously wanking him off.

Greg's mouth opened fully into a surprised "O" and his eyes rolled into the back of his head. "That's bloody good," he growled.

In a moment, pants were off, lube was uncapped, and condoms were ripped open by teeth. As soon as Lestrade had pushed in easily into Sherlock (Greg was taught by Sherlock of how to fuck a man without actually hurting him) they established a steady rhythm. Hard and slow at first, but gaining speed as they got more and more turned on.

Lestrade heard the door open and looked up.

Standing in the doorway, was his ex-wife, staring wide-eyed at the extremely debauched scene in front of her. Lestrade and her locked eyes, then she shook her head and left.

"Wait! Wait!" Lestrade screamed out the door, pulling his clothes back on. As he finally caught up with his wife, Sherlock was left on the desk, half-naked, wondering what was going on.

"This isn't what you think it is, really," Greg tried.

"It looks like your fucking a co-worker on your desk," she hissed, "or is he your boyfriend now?"

"I…I don't know what you'd call it…" Greg groped around, "Why are you here?"

"I came to see if I could talk to you, the kids have been wondering when they can visit you next, but this isn't about that, Greg, you're bumfucking a man in your office!"

"Look, this is…this is a one time thing!"

"I don't care if it's a one time thing!" his wife threw up his hands, "I'm bloody glad I divorced you. You've obviously not only lost interest in me but in _women _altogether."

Lestrade wanted to say a lot of things. I never lost interest in you. I still love you. I miss my kids. I'm sorry things didn't work out like I wanted it to. I thought you were the one that lost interest in me. I'm sorry I'm fucking a man. I don't know what I'm doing. I don't know who I am. I don't know my sexual orientation anymore. All I know is I still love you.

Take me back.

Please.

"Detective," he heard behind him, when he looked he saw Sherlock zipping his trousers back up, "Detective are you coming back to – "

"Go, Sherlock," he demanded.

"What? I thought we were going to –"

"I said, go, Sherlock!" Lestrade roared.

"Well, we still have to work on the bloody case together, and maybe we could fin-"

"SHERLOCK I WILL NOT SAY THIS AGAIN!" Lestrade roared, "I want you to leave. I want you to lose my number. I never want to see your bloody face again, okay? Just go."

"What? Lestrade, come on now, we work together."

"No, I don't want to work with you anymore, Sherlock," every word that came out of Lestrade's mouth was poison, "I don't want to see you again. You ruined my marriage."

"I didn't ruin _anything _of yours, Lestrade!" he screamed, "Your wife cheated on you and then you cheated on her. That's it. That's all there is. I refuse to stop working for you, though. I don't care if you don't want to fuck anymore, I'll just find someone else."

"So that really _was _what this was all about, wasn't it?" Lestrade roared, "That's all this fucking was to you. Just fucking, no feelings, is that it?"

"Of course it was! What, you think I have feelings for you? Check yourself, Lestrade, do you even have feelings for me?"

"It's….no…..yes, of course I do! I can't just fuck someone and leave, I can't do that. It's, I love my wife though…"

"Your ex-wife," Sherlock corrected him, "you have feelings for her and feelings for me. It's complicated and your probably confused about a lot of things if not everything. I'm leaving now. And people wonder why I don't like sentiment…"

A year later, Sherlock doesn't get triggered as much, which means he doesn't get laid as much. He works more often, and even with a marriage that's been wasted Lestrade has found a new love for his work. He doesn't think about his fling with Sherlock, and he's been single ever since.

"Lestrade," Sherlock says to him one day, "if it's any consolation…I'm sure you'll find someone."

"I'm sure you'll find someone for yourself, also, Sherlock," he says, "oh, and good luck on finding a new flat-mate, I know money's tight."

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**Author's Note - **I hope you enjoyed it, if there was any mistakes or something you didn't like, you can leave a review. If you enjoyed it, a review would be appreciated. I don't actually usually ship Sherlock with anyone else but John but the idea was in my head and I couldn't get it out. I hope you enjoyed it.


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